1. Technical Field
The present invention relates to a sheet folding apparatus for folding a sheet with an image formed thereon in half, one-third or the like, for example, and more particularly, to improvements in the folding mechanism, particularly, in the sheet transport path to perform folding processing.
2. Description of the Related Art
Generally, this type of sheet folding apparatus has been known as an apparatus for folding a sheet with an image formed thereon by an image formation apparatus such as a printing press, printer apparatus and copier in a predetermined fold position to perform finish processing. For example, Japanese Patent Application Publication No. 2009-018494 proposes an apparatus which is coupled to a sheet discharge outlet of an image formation apparatus, folds a sheet with an image formed for filing, and carries the sheet out to subsequent binding processing.
The sheet folding apparatus for thus folding a sheet in half or one-third to carry out is configured as a post-processing apparatus of the image formation apparatus, or as a unit incorporated into the image formation apparatus or binding processing apparatus. Then, as a folding form, for example, for filing, various folding forms such as ½ folding, ⅓ Z-folding and ⅓ letter-folding are known corresponding to the intended use.
The folding apparatus which is thus coupled to or incorporated into the image formation apparatus, binding apparatus (finisher apparatus, bookbinding apparatus) or the like requires a path (sheet discharge path) for carrying a sheet out to a carrying-out exit without performing the folding processing on the sheet and another path (folding processing path) for carrying a sheet out to a carrying-out exit after performing the folding processing on the sheet. Therefore, in Japanese Patent Application Publication No. 2009-018494, the sheet discharge path is provided between a carry-in entrance and carrying-out exit formed in an apparatus housing, and the folding processing path is disposed below the sheet discharge path.
Then, in the folding processing path are disposed folding rolls for folding a sheet in ½ or ⅓, and a path for causing the folding rolls to nip the sheet from the fold position. In other words, the sheet is positioned in the shape of a wing with respect to the fold position, inserted in a pair of rollers and folded.
Therefore, in the apparatus in Japanese Patent Application Publication No. 2009-018494, the sheet discharge path is disposed in the horizontal direction of the apparatus, and the folding processing path is disposed above or below in the vertical direction orthogonal to the sheet discharge path. The reason is to make the apparatus housing slim and small in the sheet discharge direction and to save the space of the footprint of the apparatus.
In an apparatus disclosed in Japanese Patent Gazette No. 4144496, a sheet carried out of an image formation apparatus is guided to a folding processing path disposed above or below in the vertical direction orthogonal to the sheet discharge direction, is folded in the path, deflected to the sheet discharge direction, and then, carried out to the outside. Similarly, in an apparatus disclosed in Japanese Patent Gazette No. 4175642, a sheet entering in the horizontal direction from a carry-in entrance is deflected to the vertical direction and guided to a folding processing path.
Thus, in the conventional apparatuses, the folding processing path is arranged in the direction orthogonal to the direction for carrying in and out the sheet. Then, the folding mechanism is disposed in the intermediate position of the path, and the path is provided in the shape of a wing in front and at the back of the folding mechanism so as to match the fold position of the sheet. In consideration of ⅓ folding, the folding processing path is configured in a path length two-thirds the length of the sheet to fold each in front and at the back of the folding mechanism.
As described above, in the conventional sheet folding apparatus, since the folding processing path and the folding mechanism are arranged on one side above or below with respect to the direction for carrying in and out the sheet, there are known a problem that the entire apparatus becomes lager, and another problem that the transport mechanism and the folding mechanism disposed in the path and the driving mechanism therefore also become larger. In other words, since the folding processing path is arranged above or below with respect to the carry-in entrance and carrying-out exit of the sheet, the path requires a path length longer than the sheet length depending on the folding form such as ⅓ folding.
Accordingly, the folding processing path and the folding mechanism occupy almost all of the space inside the apparatus, and the packing density of the processing path affects downsizing of the apparatus. Then, for example, in the conventional apparatus configuration where the folding processing path is arranged below the sheet carry-in/out path, the portion above the sheet carry-in/out path is dead space, and becomes a cause of making the apparatus larger.
Further, in the conventional apparatus, since it is forced to provide the folding mechanism in a position a considerable distance from the sheet carry-in/out path, for example, it is difficult to achieve commonality of the transport mechanism of the sheet carry-in/out path and the transport mechanism of the folding processing mechanism, resulting in increases in complexity and size.